The present disclosure relates generally to communication systems, and more particularly, to a downlink frame structure and method of downlink transmission for managing communications with one or more user equipment (UE) in a wireless communications system.
Wireless communications systems are widely deployed to provide various telecommunication services such as telephony, video, data, messaging, and broadcasts. Typical wireless communications systems may employ multiple-access technologies capable of supporting communication with multiple users by sharing available system resources (e.g., bandwidth, transmit power). Examples of such multiple-access technologies include code division multiple access (CDMA) systems, time division multiple access (TDMA) systems, frequency division multiple access (FDMA) systems, orthogonal frequency division multiple access (OFDMA) systems, single-carrier frequency division multiple access (SC-FDMA) systems, and time division synchronous code division multiple access (TD-SCDMA) systems.
These multiple access technologies have been adopted in various telecommunication standards to provide a common protocol that enables different wireless devices to communicate on a municipal, national, regional, and even global level. An example of an emerging telecommunication standard is Long Term Evolution (LTE). LTE is a set of enhancements to the Universal Mobile Telecommunications System (UMTS) mobile standard promulgated by Third Generation Partnership Project (3GPP). It is designed to better support mobile broadband Internet access by improving spectral efficiency, lower costs, improve services, make use of new spectrum, and better integrate with other open standards using OFDMA on the downlink (DL), SC-FDMA on the uplink (UL), and multiple-input multiple-output (MIMO) antenna technology. However, as the demand for mobile broadband access continues to increase, there exists a need for further improvements in LTE technology. Preferably, these improvements should be applicable to other multi-access technologies and the telecommunication standards that employ these technologies.
In wireless communications systems employing legacy LTE, a plurality of UEs served by a particular eNodeB may receive data from the eNodeB over a shared downlink channel called the Physical Downlink Shared Channel (PDSCH). In addition, control information associated with the PDSCH or may be transmitted to the UEs by the eNodeB via a Physical Downlink Control Channel (PDCCH) and/or an Enhanced PDCCH (ePDCCH). The control information included in the PDCCH or ePDCCH may include one or more uplink or downlink resource element (RE) grants for an LTE subframe. In legacy LTE, each LTE subframe has a transmission time interval (TTI) of 1 ms and is divided into two 0.5 ms slots. Any RE grants transmitted on the PDCCH, however, are for a remaining duration of the entire subframe (i.e., the full remainder of 1 ms). As such, legacy LTE does not allow for resource scheduling at a level of granularity less than a full 1 ms LTE subframe, even if faster downlink communication rates are desired for a particular communication flow.
As such, improvements in the downlink frame structure and downlink transmission methods are needed.